I've been with Media Temple almost a year now, but I recently dropped it because they were having major problems this week (which gave me a headache since it was right before the YC submission).

yeah Mediatemple has it's pros: - really good customer service (24/7) phone support - an out of this world web admin ui (nothing compares) - decent pricing

Unfortunately I can't recommend it because in the end it's about having a reliable and relatively fast website of which MT is not known for. Even with a grid server account maxed to 1GB and a separate database instance, it's still somewhat slow (and this is when their network is not being attacked...). Their technology looks really good theoritically but in real life it just doesn't work...